This invention relates to a brake pressure control device for a vehicle equipped with an anti-lock brake system (ABS), a traction control system (TCS), or other devices which electrically control the brake pressure of the wheels.
A conventional brake pressure device is explained with reference to FIG. 6. The conventional brake pressure device comprises a hydraulic unit and an electronic control unit (not shown in the diagram). The housing a of the hydraulic unit has a plural number of solenoid valves b, a fluid pressure pump, and the motor c to drive the pump.
Since each solenoid valve b is an electrical part, which may be damaged by moisture, it is covered by the bowl-shaped solenoid valve cover d. The opening side of the solenoid valve cover d is attached to the housing a and affixed by the bolt e.
Additionally, sealing material is provided on the opening side of solenoid valve cover d to secure a tight seal between the opening portion of the solenoid cover d and the housing a.
There are some difficulties in securing a sufficient sealing area at the opening portion of the solenoid valve cover.
Thus, sealability of the solenoid valve cover d depends upon the quality of the sealing materials. However, the sealing material generally deteriorates when it is used for hours or can be deteriorated by environmental changes. Therefore, the durability and reliability of the sealing in the conventional devices are some important points to be considered for improvement.
Deteriorated or damaged sealing causes water leakage from the abutting point between the opening of the solenoid valve cover d and the housing. The solenoid valves can rust or corrode as a result.
Also, as the solenoid valve cover d is placed on the two surfaces f, g of the housing in FIG. 6, difficulties in sealability increase as the number of abutting surfaces between the solenoid valve cover d and the housing increases.
With respect to conventional integral type devices where a control circuit board for controlling the electric parts is installed in a solenoid valve cover, the electronic components are apt to be damaged by water and are apt to malfunction.
Also, when affixing the solenoid-valve cover using bolts, the flat level area inside the cover decreases because of the hole which is formed on the periphery of the cover for inserting the bolt. Accordingly, the size of the control circuit board to be installed inside the cover becomes limited. The modern trend is to decrease the size of the device. Using conventional devices, however, further reduction of the size in the structure of the control circuit board is almost impossible because the bolt hole requires a certain area.